New findings confirm that many features of neuropathic pain syndromes, including spontaneous pain, mechanical allodynia (pain evoked from stimulation of Ab low threshold mechanoreceptor (LTM) afferents, cold hyperalgesia, and sensory and motor abnormalities, likely result from a central process maintained dynamically by ongoing input from a site of peripheral injury. Local anesthesia of these sites but not adjacent sites (both within an area of Ab-LTM mechanical allodynia) alleviates all symptoms for the duration of the local anesthetic. Thus the relief is not likely due to non-specific effects of the local anesthetic or to a placebo effect. In a subset of patients with peripheral injury, modification of circulation by limb elevation or occlusion by a tourniquet abolished all symptoms within 2-6 minutes, too soon to result from neural blockade. Experiments using limb elevations and cuff blocks have incorporated placebo controls and identified two patterns of relief; one apparently related to limb perfusion and one apparently related to suppression of circulating epinephrine. Capsaicin an active ingredient in chili pepper, was injected into the volar forearm or dorsum of the foot in normal volunteer subjects. Injection of 100 mg produced both spontaneous pain and in some cases an area of mechanical allodynia which also appeard to be Ab-LTM mediated. This effect was observed in only one-half of the experiments. Increasing the dose up to 500 mg also produced variable amounts of mechanical allodynia which does not appear to be dose-related.